Sheet metal edges can be sharp and unsafe to handle, causing potential damage to people or other material in their proximity. One way to prevent these edges from causing damage is to bend the end of the sheet metal back against itself in a way that creates a smoother rounded edge or hem. For example, in FIG. 1, a sheet metal piece 80 is shown in cross section with sharp edges 82. In order to present a smooth rounded hem 84 to improve safety during handling and in application, the sheet metal piece end has been bent back on itself to form what is called a hem 84.
Hems like this are sometimes formed by a brake press that bends the sheet metal end onto itself between two opposed die heads. In practice, this is a challenging operation that requires that the sheet metal be held firmly in place while the die heads form the hem. Further, the initial bending operation may be done by driving a punch into a die, then completing the bend between the opposed die heads. Either approach requires multiple steps and multiple manipulations of the sheet metal, and thus makes it difficult to use a continuous sheet that can be fed through a machine. The machine described herein improves on the known methods.